Heat exchanger having a head with an integral radiation shield

ABSTRACT

A heat exchanger having a radiation shield integral with the head and having a removable downcomer for providing access to stationary and floating head tube sheets by a remote control device when the downcomer is removed from the heat exchanger.

United States Patent [191 Sturiale et al.

[ HEAT EXCHANGER HAVING A HEAD WITH AN INTEGRAL RADIATION SHIELD [75] Inventors: Louis A. Sturiale, Tampa; Remco P.

Waszink, St. Petersburg, both of Fla.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

22 Filed: Apr. 12, 1971 21 Appl. No.: 132,975

[52] U.S. Cl. 1.65/134, 176/87 [51] Int. Cl F281 19/00 [58] Field of Search 165/74, 135, 134, 157,

[56] References Cited UNITED STATES PATENTS 2,853,624 9/1958 Wigner et al. 176/87 X 5] Dec. 31, 1974 3,059,908 10/1967 Fox et a1 165/157 3,187,807 6/1965 Ammon.....

3,379,616 4/1968 Vitry 3,520,356 7/1970 Bell et al 165/135 Primary Examiner-Kenneth W. Sprague Attorney, Agent, or Firm-F. J. Baehr, Jr.

[5 7] ABSTRACT A heat exchanger having a radiation shield integral with the head and having a removable downcomer for providing access to stationary and floating head tube sheets by a remote control device when the downcomer is removed from the heat exchanger.

4 Claims, 4 Drawing Figures Patented Dec. 31, 1974 3 Sheets-Sheet 1 Patented Dec. 31,- 1974 3 Sheets-Sheet 2 FIG. IB

@v lull' Patented Dec. 31, 1974 3,857,442

$ Sheets-Sheet 5 HEAT EXCHANGER HAVING A HEAD WITH AN INTEGRAL RADIATION SHIELD BACKGROUND OF THE INVENTION This invention relates to heat exchangers, and more particularly, to a heat exchanger having a radiation shield made integral with a stationary head and having a removable downcomer which provides access to the stationary and floating heads when the downcomer is removed.

The demand for electrical power in the United States approximately doubles every years. Presently, fossil fuel provides the majority of the heat energy to produce the needed electrical power. In the next 30 years,

it is estimated that over 50 percent of our electrical power will be produced by nuclear energy. The supply of fissionable material is limited, so that the future of nuclear power depends on developing a fast breeder reactor which produces more fissionable material than it consumes. Such a system, to become operational, necessarily requires sound heat exchangers which can be inspected and serviced with a minimum amount of remote control equipment, as remote control equipment is initially expensive and it is expensive to maintain.

Based on the present technology, it is contemplated to utilize sodium as the heat transfer medium to cool the core of the fast breeder reactor and water and steam in the power generation portion of the cycle. Because it is inevitable a leak will occur in any heat exchanger containing sodium and water, it is considered imperative not to utilize radioactive sodium and water or steam in the same heat exchanger. Therefore, an intermediate heat exchanger, transferring heat from radioactive to non-radioactive sodium, is required to produce an operable system which is safe from a radioactive sodium upset.

SUMMARY OF THE INVENTION In general, a heat exchanger for transferring heat from a primary radioactive fluid to a second fluid which is not radioactive comprises a tube bundle having a head portion, the head portion having inlet and outlet conduits for allowing the secondary fluid to flow through the tube bundle, a shell for containing the primary fluid and the tube bundle, one end of the shell being open, the head portion being adapted to plug the opening, and a radiation shield associated with the head so that the secondary fluid inlet and outlet conduits can be disconnected from the head, and the head can be disconnected from the shell without subjecting workmen to dangerous levels of radiation from the primary fluid.

BRIEF DESCRIPTION OF THE DRAWINGS The objects and advantages of this invention will become more apparent from reading the following detailed description in connection with the accompanying drawings, in which:

FIG. 1A is a vertical sectional view of the upper half of a heat exchanger made in accordance with this invention;

FIG. 1B is a vertical sectional view of the lower half of the heat exchanger;

FIG. 2 is a plan view of the heat exchanger; and

FIG. 3 is a sectional view of the heat exchanger taken on line III-III of FIG. 1A.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, FIGS. 1A and 1B show an intermediate heat exchanger 1 for a liquid metal fast breeder reactor (not shown) which is adapted to transfer heat from a primary fluid, radioactive liquid sodium utilized to cool the nuclear reactor, to a secondary fluid, liquid sodium, which is utilized in a steam generator (not shown) to heat steam to drive a turbogenerator (not shown) to produce electricity. The secondary sodium is not radioactive. The primary sodium is subjected to bombardment by a high flux of neutrons in the reactor and becomes radioactive; however, when it decays, it emits gamma radiation and bombardment of the secondary sodium by gamma radiation does not make the secondary sodium radioactive.

The heat exchanger 1, as shown in FIGS. 1A and 18, comprises a tube bundle 3, a stationary head portion 5 disposed on the upper end of the tube bundle, a floating head 7 disposed on the lower end of the tube bundle, and an outer shell 9 containing the tube bundle 3. The tube bundle 3 comprises a plurality of straight tubes 11, or generally straight tubes with a local half sine wave bend disposed therein, fastened to tube sheets 13 and 15 of the stationary and floating heads 5 and 7, respectively, by welding or other means, and a centrally disposed tube 17 substantially larger in diameter than the generally straight tubes 11. The larger tube or inner sleeve 17 is also fastened to the tube sheets 13 and 15 by welding or other means. The tube bundle 3 is generally enclosed in an outer sleeve 19 extending generally from head to head. The centrally disposed tube 17 and outer sleeve 19 generally define an annular space through which the generally straight tubes 11 extend.

A secondary fluid inlet conduit 21 and a secondary fluid outlet conduit 23 direct the secondary fluid, sodium liquid, to and from the tube bundle 3. The secondary fluid outlet conduit 23 is connected to and in communication with the stationary head 5.

As shown in FIG. IA, the secondary fluid inlet conduit 21 comprises a vertical tubular portion 25, and a lateral tubular portion 27 disposed normal to the vertical portion 25. The vertical tubular portion 25 is axially aligned with the large centrally disposed tube 17 of the tube bundle 3 and generally has the same cross sectional areas as the large centrally disposed tube 17. The lower portion of the vertical tubular portion 25 is welded to the stationary head and has a flange 29 disposed on the upper end thereof. A tubular downcomer or inner sleeve 31 is adapted to slidably engage or telescope within the vertical portion 25 of the secondary fluid inlet conduit 21 and the large centrally located tube 17 of the tube bundle 3. The tubular downcomer 31 has an opening 33, which registers with the lateral portion 27 of the inlet conduit 21 so that secondary fluid flows from the lateral portion 27 of the inlet conduit 21 downwardly through the tubular downcomer 31, through the lower portion of the centrally located tube 17,'into the floating head 7, upwardly through the generally straight tubes 11, then into the stationary head 5 and out the outlet conduit 23, as indicated by the arrows having solid shafts.

The diameter of the downcomer 31, the vertical tubular portion 25 of the secondary fluid inlet 21 and the large centrally located tube 17 are such that the amount of fluid which bypasses the generally straight tubes 11 as the secondary fluid flows from the inlet to the outlet conduits 21 and 23, respectively, is minimal.

As shown in FIGS. 1A and 1B, the shell 9 generally enwraps the tube bundle 3 and the upper end of the shell 9 is open to allow the tube bundle 3 to be removed therefrom. A primary fluid inlet conduit 35 is disposed in a wall portion 36 of the shell 9 adjacent the open end, and a primary fluid outlet conduit 37 is disposed in a lower shell cover 39, closing the lower end of the outer shell 9.

The outer sleeve 19 enwrapping the tube bundle 3 has a plurality of openings 41 and 43 adjacent the stationary and floating heads and 7, respectively. As shown in FIGS. 1A and 3, an eccentric liner 45 is disposed adjacent the primary liquid inlet conduit 35 and is welded to the shell 9 adjacent the inlet conduit 35 to distribute the influent primary fluid evenly to the openings 41 in the outer sleeve 19 of the tube bundle 3. A seal ring 47 is disposed adjacent the lower portion of the eccentric liner 45 to cause essentially all of the influent primary fluid to flow through the upper openings 41 in the outer sleeve 19, down the annular space between the inner centrally located tube 17 and the outer sleeve 19 in counterflow relation to the flow of secondary fluid flowing up the inside of the generally straight tubes 11, thus providing natural circulation capability to both primary and secondary fluid as they flow through the heat exchanger. The primary fluid then flows out of the lower openings 43 in the outer sleeve 19 and to the primary fluid outlet conduit 37 as indicated by the arrows with dashed lines forming the shafts.

A space between the outer sleeve 19 and the shell 9 provides a quiescent zone which reduces the heat loss from the heat exchanger. A thermal shield 48 substantially seals off the area above the eccentric liner 45 to provide another quiescent zone surrounding the stationary head to protect the joints of the tubes 11 and tube sheet 13 from the corrosive action of the circulating liquid sodium.

The shell is hung from a thick floor 49 by a plurality of supports 51. The floor 49 is formed of approximately six feet of concrete to provide a radiation shield for the heat exchanger. The open end of the shell 9 extends partially into a well-like opening 52 in the concrete floor. A portion of the shell 53 adjacent the opening is expanded outwardly. The stationary head 5 of the tube bundle 3 plugs the opening in the shell 9. The upper portion of the stationary head 5 forms a radiation shield 55 and comprises a cylindrical collar or liner 57, a spherical portion 59, closes one end of the collar 57 and provides a cover for a plenum chamber in the stationary head, and a flat cover plate 61 closes the other end of the collar 57, forming a compartment which is filled with steel shots 63 to provide a radiation shield integral with the stationary head 5. The secondary fluid inlet and outlet conduits 21 and 23, respectively, extend through the shield 55 and the upper flanged end 65 of the downcomer tube 31 is also provided with an integral radiation shield 67, as shown in FIG. 1A.

The diameter of the radiation shield 55 integral with the head 5 is generally as large as the shell 9 to shield the area above the shell so that the head 5 can be disconnected from the shell 9 by workmen coming in direct contact with the upper end of the shell without subjecting the workmen to dangerous amount of irradiation.

A thick concrete cover 69 covers the well-like opening 52in the concrete floor 49 to provide additional radiation shielding during normal operation. The concrete cover 69 has a central opening 71 disposed so the downcomer tube 31 may be removed from the heat exchanger 1 without removing the cover 69. Thus, the tubes 11 and tube sheets 13 and 15 can be inspected and serviced through the opening provided when the downcomer 31 is removed by utilizing some type of remote control inspection and maintenance device. A small plug 73 covers the opening 71 when the heat exchanger is in operation to provide maximum radiation shielding.

The secondary inlet and outlet conduits 21 and 23 are disposed in the well-like opening 52 and they may be disconnected by direct contact means by workmen entering the well-like opening without subjecting the workmen to dangerous levels of radiation. Thus, the secondary fluid inlet and outlet conduits 21 and 23 may be disconnected from the stationary head 5, and the stationary head 5 may be disconnected from the shell 9 by direct contact means without subjecting the workmen to dangerous levels of radiation from the primary fluid, radioactive sodium, to reduce the amount and complexity of the remote control equipment necessary to inspect a heat exchange made in accordance with this invention.

What is claimed is:

1. A heat exchanger for transferring heat from a primary radioactive fluid to a secondary fluid, said heat exchanger comprising a shell, and a tube bundle disposed in said shell, said tube bundle having a stationary head and a floating head, a plurality of generally straight tubes extending between said heads, a centrally disposed tube substantially larger than said generally straight tube, and an outer sleeve enwrapping the generally straight tubes, said centrally disposed tube and said outer sleeve forming an annular space through which the generally straight tubes extend, the outer sleeve having a plurality of openings adjacent the stationary head and adjacent the floating head, said stationary head having inlet and outlet conduits for allowing secondary fluid to flow through said tube bundle, and a radioactive shield associated therewith so that said secondary fluid inlet and outlet conduits may be disconnected from said stationary head and said stationary head can be disconnected from said shell and said heat exchanger further comprising primary fluid inlet and outlet conduits and a seal ring disposed between said shell and said outer sleeve to cause the primary fluid to flow from said primary inlet conduit through said openings in one end of said outer sleeve, through said annular space in counterflow relation to the secondary fluid flowing through said straight tubes and through openings in the other end of said outer sleeve, and then to said primary outlet conduit, and a space between said outer sleeve and said shell providing a quiescent zone for said primary liquid.

2. A heat exchanger for transferring heat from a primary radioactive fluid to a secondary fluid, said heat exchanger comprising:

a tube bundle having a head portion,

said head portion having inlet and outlet conduits for allowing secondary fluid to flow through said tube bundle,

a shell for containing said primary fluid and said tube bundle,

one end of said shell being open and said head portion being adapted to plug said opening,

said head portion having a radiation shield associated therewith so that said secondary fluid inlet and outlet may be disconnected from said head and said head can be disconnected from said shell,

said radiation shield comprising a cylindrical/liner attached to the head portion, the head portion closing one end thereof, and a cover plate closing the other end of said liner to form an enclosed space,

which is fllled with steel shot.

3. A heat exchanger as set forth in claim 2 and further comprising a primary inlet conduit disposed in a wall of the shell adjacent the heat portion of the tube bundle, an eccentric shell liner disposed adjacent said primary inlet conduit and fastened to said wall adjacent each side of said primary inlet conduit to distribute primary influent liquid to the outside of the tubes of the tube bundle.

4. A heat exchanger as set forth in claim 2 and further comprising a shield substantially blocking the flow of said primary fluid to an area surrounding the head portion to form a quiescent zone in this area. 

1. A heat exchanger for transferring heat from a primary radioactive fluid to a secondary fluid, said heat exchanger comprising a shell, and a tube bundle disposed in said shell, said tube bundle having a stationary head and a floating head, a plurality of generally straight tubes extending between said heads, a centrally disposed tube substantially larger than said generally straight tube, and an outer sleeve enwrapping the generally straight tubes, said centrally disposed tube and said outer sleeve forming an annular space through which the generally straight tubes extend, the outer sleeve having a plurality of openings adjacent the stationary head and adjacent the floating head, said stationary head having inlet and outlet conduits for allowing secondary fluid to flow through said tube bundle, and a radioactive shield associated therewith so that said secondary fluid inlet and outlet conduits may be disconnected from said stationary head and said stationary head can be disconnected from said shell and said heat exchanger further comprising primary fluid inlet and outlet conduits and a seal ring disposed between said shell and said outer sleeve to cause the primary fluid to flow from said primary inlet conduit through said openings in one end of said outer sleeve, through said annular space in counterflow relation to the secondary fluid flowing through said straight tubes and through openings in the other end of said outer sleeve, and then to said primary outlet conduit, and a space between said outer sleeve and said shell providing a quiescent zone for said primary liquid.
 2. A heat exchanger for transferring heat from a primary radioactive fluid to a secondary fluid, said heat exchanger comprising: a tube bundle having a head portion, said head portion having inlet and outlet conduits for allowing secondary fluid to flow through said tube bundle, a shell for containing said primary fluid and said tube bundle, one end of said shell being open and said head portion being adapted to plug said opening, said head portion having a radiation shield associated therewith so that said secondary fluid inlet and outlet may be disconnected from said head and said head can be disconnected from said shell, said radiation shield comprising a cylindrical/liner attached to the head portion, the head portion closing one end thereof, and a cover plate closing the other end of said liner to form an enclosed space, which is filled with steel shot.
 3. A heat exchanger as set forth in claim 2 and further comprising a primary inlet conduit disposed in a wall of the shell adjacent the heat portion of the tube bundle, an eccentric shell liner disposed adjacent said primary inlet conduit and fastened to said wall adjacent each side of said primary inlet conduit to distribute primary influent liquid to the outside of the tubes of the tube bundle.
 4. A heat exchanger as set forth in claim 2 and further comprising a shield substantially blocking the flow of said primary fluid to an area surrounding the head portion to form a quiescent zone in this area. 